Data storage systems are used to store information provided by one or more host computer systems. Such data storage systems receive requests to write information to one or more data storage devices, and requests to retrieve information from those one or more data storage devices. Upon receipt of a write request, the system stores information received from a host computer in a data cache. In some storage systems, a copy of that information is also stored in a nonvolatile storage device. Upon receipt of a read request, the system recalls information from the one or more data storage devices and moves that information to the data cache. Thus, the system is continuously moving information to and from a plurality of data storage devices, and to and from the data cache.
Data storage systems can comprise a plurality of enclosures, wherein certain of those enclosure comprise data storage device enclosures comprising a plurality of data storage devices. A system controller communicates with the plurality of enclosures using a communication protocol, such as for example a Fibre Channel protocol. In addition, each enclosure is in communication with one or two adjacent enclosures.